Ultrasonic hair styling

ABSTRACT

A hair styler uses ultrasound at an ultrasound frequency of at least 1 MHz to get a non-chemical hair styling. Advantageously, the ultrasound frequency is between 1 and 100 MHz, preferably between 3 and 10 MHz, and more preferably between 3 and 5 MHz. The ultrasound energy is preferably applied at a power that is at least 1 W/cm2, and preferably does not exceed 10 W/cm2, such as 6 W/cm2. The invention may be used for hair curling and for hair straightening. A hair straightening method comprises temporarily straightening hair, and applying ultrasound to temporarily straightened hair to obtain straightened hair. Advantageously, ultrasound is applied during a period of between 5 seconds and 2 minutes, and preferably during about 10 seconds.

FIELD OF THE INVENTION

The invention relates to ultrasonic hair styling, such as ultrasonic hair curling, crimping, or straightening.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 6,196,236 discloses an ultrasonic hair curling device capable of applying ultrasonic vibration efficiently to hairs for effective hair styling in a short time. The device includes a housing, an ultrasonic generator incorporated in the housing for generating ultrasonic vibrations, and a horn connected to receive and transmit the ultrasonic vibrations at a frequency of 20 kHz to 100 kHz. The horn is formed at its end with a hollow barrel which projects from the housing for receiving therearound a strand of hair to be curled. The hollow barrel is provided at a portion intermediates at its longitudinal ends with a hair winding zone of which cross-section is smaller than the other portion of the hollow barrel. The hair winding zone of the reduced cross section can vibrate at an amplitude larger than at the front end of the barrel for applying the ultrasonic vibrations efficiently to the hair and making the hair curling effectively.

EP 1 728 450 discloses an ultrasonic hair treatment device to apply ultrasonic vibrations to a user's hair for enhancing the penetration of a hair treatment composition into the hair. A piezoelectric transducer produces vibrations of 500 kHz to 10 MHz frequency at a power of 0.1 to 5 W/cm².

SUMMARY OF THE INVENTION

It is, inter alia, an object of the invention to provide a more effective ultrasonic hair styling without using chemicals to obtain the hair styling effect. The invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims. In the claims, the expression “to get a non-chemical hair styling” is meant to reflect that no chemicals are used to obtain the hair styling effect, i.e. the hair styling effect directly results from applying ultrasound, possibly to hair that is mechanically put into a certain shape (e.g. by winding it around a rod, or by stretching), which shape is retained as a result of applying ultrasound to the hair.

The inventors have found that for an effective hair styling without using chemicals such as the hair treatment composition of EP 1 728 450, the ultrasound frequency should be at least 1 MHz, and preferably exceeds 1 MHz. In a particular embodiment, the ultrasound frequency is between 1 and 100 MHz, preferably between 3 and 10 MHz, and more preferably between 3 and 5 MHz. In this invention, the hairs are styled by the MHz ultrasound waves, which involve a combination of heating due to the dissipation of the wave and mechanical displacement of the ultrasound propagation through the hair. In the kHz range, the thermal effect is not present due to low dissipation of the ultrasound at these frequency. If the frequency is lowered, the thermal effect decreases and the mechanical effect increases, while if the frequency is increased, the mechanical effect decreases and the thermal effect increases. At too high frequencies, the hairs would be damaged in a similar way as in standard thermal curling devices. At frequencies above 100 MHz, the ultrasound wave will be dissipated within the first layer of hairs and thus the next layers will not have any effect from the ultrasound, and the curling would then rely only from the heat diffusion in a similar way to a hot plate as in usual thermal curling devices, which may result in damaging the hair.

Good results were obtained with a power of the ultrasound of at least 1 W/cm², and which preferably does not exceed 10 W/cm², such as 6 W/cm². From a power of 1 W/cm² a curling effect can be perceived. The effect would be still present at powers of 10 W/cm² and higher. However the temperature of the hair and the temperature of the transducer will increase at increased power levels. Good results were obtained with a treatment time of about 10 seconds to 1 minute.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 4 illustrate embodiments of a hair curler device in accordance with the present invention;

FIG. 5 shows an embodiment of a hair crimper or waver device in accordance with the present invention; and

FIG. 6 shows an embodiment of a hair straightening device in accordance with the present invention.

DESCRIPTION OF EMBODIMENTS

To implement the invention, it is basically possible to use similar hardware as shown in the prior art of U.S. Pat. No. 6,196,236. However, the parameter settings (frequency, power) need to be in line with the appended claims.

FIG. 1 illustrates a first embodiment of a hair curler device in accordance with the present invention. Hair H is wound around a cylindrical rod, and an ultrasonic transducer UST, preferably using PZT or CMUT technology, moves and presses the hair. Herein, PZT stands for Lead Zirconate Titanate, and CMUT stands for Capacitive Micromachined Ultrasonic Transducers.

FIG. 2 illustrates a second embodiment of a hair curler device in accordance with the present invention. In FIG. 2, the ultrasonic transducer UST is embedded inside the cylindrical rod on which the hair H is wound around.

FIG. 3 illustrates a third embodiment of a hair curler device in accordance with the present invention. In FIG. 3, ultrasonic transducer UST generates the ultrasound waves which are coupled into the conical rod R. The hair H is wound around the conical rod R.

FIG. 4 illustrates a fourth embodiment of a hair curler device in accordance with the present invention. In FIG. 4, the ultrasonic transducer UST generates the ultrasound waves which are coupled into a cylindrical rod R containing features F. The hair H is wound around the cylindrical rod R within the features F. The features F may be slots with a width between 0.2 mm and 4 mm.

In an alternative embodiment, the surface of the rod as illustrated in the previous embodiments may contain features smaller than 0.2 mm. These features may be made from the rod material itself or from an additional coating on the rod.

FIG. 5 illustrates an embodiment of a hair crimper or waver device in accordance with the present invention. In FIG. 5, ultrasonic transducer UST generates the ultrasound waves which are coupled into two similar rods R mounted on the upper side of a clamping device. A third rod with two recesses on its sides are mounted on the lower side of the same clamping device such that when the hair H is placed in between the upper and lower sides of the clamping device and the clamping device is clamped by the user, the third rod sits between the first and second rods, pressing the hair into a crimped or waved shape as shown in FIG. 5.

While one application of the invention relates to hair curling, it is alternatively possible to use the invention for hair straightening. To this end, the curled hair needs to be placed straight before applying the treatment. This can be done by stretching the hair, but also by guiding the hair before clamping it between two plates. In fact, if the hairs are simply clamped in their original curled shape, the straightening effect would not work. One could use a normal clamp-based hair straightener in which the heating elements are replaced by ultrasound elements. Another embodiment would be a hair stretching element placed in front of the ultrasound transducer to stretch the hair before treatment. Yet another embodiment would be a comb placed in front of a clamp to guide the hair straight into the clamp, the clamp being made of an ultrasound transducer.

FIG. 6 illustrates an embodiment of a hair straightening device in accordance with the present invention. In FIG. 6, ultrasonic transducer UST generates the ultrasound waves on a plate on the lower or upper side of a clamping device. A stretcher S is mounted on one side of the plate such that when the hair H is placed in between the upper and lower sides of the clamping device, the clamping device is clamped by the user and the device is moved, the stretcher S stretches the hairs clamped between the two plates to form a straight shape.

Embodiments of the invention thus provide an ultrasonic treatment of hair whereby a larger volume of hair can be treated in order to get hair styling without any chemicals and without any thermal damage to the hair as it is done in hot iron styling devices. The hair styling by means of ultrasound using the parameters described herein is done not by heating the hair or using chemicals but by mechanical way of breaking hydrogen bonds to style hairs using ultrasound.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 

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 9. A hair styling method of applying ultrasound at an ultrasound frequency to hair to get a non-chemical hair styling, wherein the ultrasound frequency is at least 3 MHz, and the hair styling effect directly results from applying ultrasound to hair without applying chemicals or heat to hair.
 10. A hair styling method as claimed in claim 9, wherein the ultrasound frequency is between 3 and 100 MHz, preferably between 3 and 10 MHz, and more preferably between 3 and 5 MHz.
 11. A hair styling method as claimed in claim 9, wherein a power of the ultrasound is at least 1 W/cm².
 12. A hair styling method as claimed in claim 11, wherein the ultrasound power does not exceed 10 W/cm², such as 6 W/cm².
 13. A hair styling method as claimed in claim 1, comprising temporarily straightening hair, and applying ultrasound to temporarily straightened hair to obtain straightened hair.
 14. A hair styling method as claimed in claim 1, comprising winding hair (H) around a rod (R), and applying ultrasound to hair (H) wound around the rod (R).
 15. A hair styling method as claimed in claim 1, wherein ultrasound is applied during a period of between 5 seconds and 2 minutes, and preferably during about 10 seconds.
 16. A hair styler arranged for applying ultrasound at an ultrasound frequency to hair for carrying out a method as claimed in claim 1 to get a non-chemical hair styling, wherein the ultrasound frequency is at least 3 MHz, and the hair styling effect directly results from applying ultrasound to hair without applying chemicals or heat to hair.
 17. A hair styler as claimed in claim 16, comprising means for temporarily straightening the hair, and an ultrasound transducer (UST) for applying ultrasound to temporarily straightened hair to obtain straightened hair.
 18. A hair styler as claimed in claim 16, comprising a rod (R) around which hair (H) can be wound, and an ultrasound transducer (UST) for applying ultrasound to hair (H) wound around the rod (R).
 19. A hair styler as claimed in claim 16, comprising: a first rod (R) mounted on a first side of the hair styler; an ultrasound transducer (UST) for generating ultrasound waves which are coupled into the first rod (R); a second rod with a recess for receiving the first rod on its side, on a second side of the hair styler, whereby when hair (H) is placed in between the first and second sides of the hair styler, and the first and second sides of the hair styler are clamped together, the hair (H) is pressed into a crimped or waved shape.
 20. A hair styler as claimed in claim 16, comprising an ultrasound transducer (UST) for applying ultrasound during a period of between 5 seconds and 2 minutes, and preferably during about 10 seconds.
 21. A hair styler as claimed in claim 16, wherein the ultrasound frequency is between 3 and 100 MHz, preferably between 3 and 10 MHz, and more preferably between 3 and 5 MHz.
 22. A hair styler as claimed in claim 16, wherein a power of the ultrasound is at least 1 W/cm².
 23. A hair styler as claimed in claim 22, wherein the ultrasound power does not exceed 10 W/cm², such as 6 W/cm².
 24. A hair styler as claimed in claim 16, comprising temporarily straightening hair, and applying ultrasound to temporarily straightened hair to obtain straightened hair. 